1. Field of the Invention
The present invention relates to a vehicle power train control apparatus. More specifically, the present invention relates to a vehicle power train control apparatus configured and arranged to control a vehicle power train so that an operation of the vehicle power train matches an operation mode of the vehicle determined based on vehicle driving information.
2. Background Information
A conventional automatic transmission, including a continuously variable transmission, is configured and arranged to determine a target transmission input rotation rate and a target gear according to a speed of a vehicle as well as an accelerator position and a throttle position that are indicative of an engine load by referring to a predetermined map. The conventional automatic transmission is then configured and arranged to shift gears so that the transmission input rotation rate and a selected gear are switched to the target transmission input rotation rate and the target gear, respectively.
In such conventional automatic transmission, the control over the shifting of gears is unambiguously determined by the predetermined map. Therefore, it is impossible to control the shifting of the gears in a manner that is suited to all driving tendencies, which vary widely in accordance with road conditions and driver's personal preferences. For example, when a swift and fast-paced type of travel is desired, a low gear ratio is preferably used. Also, when travelling a continuously winding road such as a mountain road, maintaining a low gear ratio is preferred over frequent and repeated shifting of gears.
Therefore, Japanese laid-Open Patent Application Publication No. 07-280076 and Japanese Laid-Open Patent Application Publication No. 07-243516 disclose a method for controlling gear changes in an automatic transmission in which data relating the vehicle operation is analyzed to determine the driving tendency. The data relating the vehicle operation includes accelerator position, rate of change in the accelerator position, vehicle speed, front to rear acceleration of a vehicle body, braking operation, steering angle, lateral acceleration toward the vehicle body, yaw rate toward the vehicle body, navigational (GPS) information, and the like. Then, the driving force is controlled in accordance with the driving tendency that is determined based on the vehicle operation information.
According to such conventional method for controlling the shifting of gears as disclosed in the above mentioned references, even during a high-speed travel with a low accelerator position in which the vehicle is usually upshifted into a higher gear, it is possible to maintain a lower gear ratio or downshift to a lower gear ratio if the driving tendency indicates reacceleration of the vehicle will be required. Thus, the desired acceleration performance can be achieved when the acceleration position is subsequently raised to reaccelerate the vehicle. The sufficient reacceleration performance required by the driver can accordingly be provided.
Moreover, the driving tendency is determined such that reacceleration of the vehicle will be required, for example, when traveling on a continuously winding road such as a mountain road. In the conventional method for controlling the shifting of gears as disclosed in the above mentioned references, the gear shift control is changed in accordance with this driving tendency so that a relatively low gear ratio will be maintained. As a result, it is possible to avoid repeated upshifting caused by the driver releasing his/her foot from the accelerator pedal when approaching a curve (corner or bend) in a road, and repeated downshifting caused by reacceleration when the driver depresses the accelerator pedal on coming out of the curve. By controlling the shifting of gears according to the driving tendency, the driver can navigate the winding road in a swift manner with the low gear ratio being maintained.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved vehicle power train control apparatus. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.